The Star Trek Experience ran from 1998 - 2008 in the Las Vegas Hilton Casino.
It had a restaurant (Quark's Bar), shops (the Promenade) and a Museum with props.
It opened with only an 18 minute motion simulator. A second 18 minute show was added in 2004.
You could do both attractions, visit the museum and eat at the restaurant in under 2 hours.
There really was not enough "content" for fans to make dedicated trips to Vegas.
I visited it twice. One trip was to specifically see it. The other was during a convention.
Star Trek Voyager went off the air in 2001. Star Trek Enterprise went off the air in 2005.
There were no Star Trek movies between 2003 - 2008.
The lack of new Star Trek shows and movies may have contributed to the decrease in attendance.
Below is a Virtual tour:
http://www.digitalproperties.ca/exp2/slideshow5.php
Note the slot machines right outside the attraction (Slide 4). Not very family friendly.
I believe a Star Trek themed attraction would work better in Orlando than in a Vegas casino.